﻿using System;

namespace DrawEngine.Renderer.Mathematics.Random
{
    /// <summary>
    /// implements the Halton Quasi Monte Carlo generator algorithm
    ///
    /// All the theory and the implementation can be found in:
    /// http://www.puc-rio.br/marco.ind/quasi_mc.html
    ///
    /// </summary>
    public sealed class QMCHaltonRandom : IRandom
    {
        #region Parameters
        /// <summary>
        /// Maximum int value
        /// </summary>
        private const int maxLong = 1000;
        /// <summary>
        /// List of prime numbers
        /// </summary>
        private readonly int[] primeNumbers = {
                                                      2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67,
                                                      71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149,
                                                      151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229
                                                      , 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311,
                                                      313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401
                                                      , 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487,
                                                      491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593
                                                      , 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673,
                                                      677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773
                                                      , 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877,
                                                      881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983
                                                      , 991, 997, 1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061,
                                                      1063, 1069, 1087, 1091, 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151,
                                                      1153, 1163, 1171, 1181, 1187, 1193, 1201, 1213, 1217, 1223, 1229, 1231,
                                                      1237, 1249, 1259, 1277, 1279, 1283, 1289, 1291, 1297, 1301, 1303, 1307,
                                                      1319, 1321, 1327, 1361, 1367, 1373, 1381, 1399, 1409, 1423, 1427, 1429,
                                                      1433, 1439, 1447, 1451, 1453, 1459, 1471, 1481, 1483, 1487, 1489, 1493,
                                                      1499, 1511, 1523, 1531, 1543, 1549, 1553, 1559, 1567, 1571, 1579, 1583,
                                                      1597, 1601, 1607, 1609, 1613, 1619, 1621, 1627, 1637, 1657, 1663, 1667,
                                                      1669, 1693, 1697, 1699, 1709, 1721, 1723, 1733, 1741, 1747, 1753, 1759,
                                                      1777, 1783, 1787, 1789, 1801, 1811, 1823, 1831, 1847, 1861, 1867, 1871,
                                                      1873, 1877, 1879, 1889, 1901, 1907, 1913, 1931, 1933, 1949, 1951, 1973,
                                                      1979, 1987, 1993, 1997, 1999, 2003, 2011, 2017, 2027, 2029, 2039, 2053,
                                                      2063, 2069, 2081, 2083, 2087, 2089, 2099, 2111, 2113, 2129, 2131, 2137,
                                                      2141, 2143, 2153, 2161, 2179, 2203, 2207, 2213, 2221, 2237, 2239, 2243,
                                                      2251, 2267, 2269, 2273, 2281, 2287, 2293, 2297, 2309, 2311, 2333, 2339,
                                                      2341, 2347, 2351, 2357, 2371, 2377, 2381, 2383, 2389, 2393, 2399, 2411,
                                                      2417, 2423, 2437, 2441, 2447, 2459, 2467, 2473, 2477, 2503, 2521, 2531,
                                                      2539, 2543, 2549, 2551, 2557, 2579, 2591, 2593, 2609, 2617, 2621, 2633,
                                                      2647, 2657, 2659, 2663, 2671, 2677, 2683, 2687, 2689, 2693, 2699, 2707,
                                                      2711, 2713, 2719, 2729, 2731, 2741, 2749, 2753, 2767, 2777, 2789, 2791,
                                                      2797, 2801, 2803, 2819, 2833, 2837, 2843, 2851, 2857, 2861, 2879, 2887,
                                                      2897, 2903, 2909, 2917, 2927, 2939, 2953, 2957, 2963, 2969, 2971, 2999,
                                                      3001, 3011, 3019, 3023, 3037, 3041, 3049, 3061, 3067, 3079, 3083, 3089,
                                                      3109, 3119, 3121, 3137, 3163, 3167, 3169, 3181, 3187, 3191, 3203, 3209,
                                                      3217, 3221, 3229, 3251, 3253, 3257, 3259, 3271, 3299, 3301, 3307, 3313,
                                                      3319, 3323, 3329, 3331, 3343, 3347, 3359, 3361, 3371, 3373, 3389, 3391,
                                                      3407, 3413, 3433, 3449, 3457, 3461, 3463, 3467, 3469, 3491, 3499, 3511,
                                                      3517, 3527, 3529, 3533, 3539, 3541, 3547, 3557, 3559, 3571, 3581, 3583,
                                                      3593, 3607, 3613, 3617, 3623, 3631, 3637, 3643, 3659, 3671, 3673, 3677,
                                                      3691, 3697, 3701, 3709, 3719, 3727, 3733, 3739, 3761, 3767, 3769, 3779,
                                                      3793, 3797, 3803, 3821, 3823, 3833, 3847, 3851, 3853, 3863, 3877, 3881,
                                                      3889, 3907, 3911, 3917, 3919, 3923, 3929, 3931, 3943, 3947, 3967, 3989,
                                                      4001, 4003, 4007, 4013, 4019, 4021, 4027, 4049, 4051, 4057, 4073, 4079,
                                                      4091, 4093, 4099, 4111, 4127, 4129, 4133, 4139, 4153, 4157, 4159, 4177,
                                                      4201, 4211, 4217, 4219, 4229, 4231, 4241, 4243, 4253, 4259, 4261, 4271,
                                                      4273, 4283, 4289, 4297, 4327, 4337, 4339, 4349, 4357, 4363, 4373, 4391,
                                                      4397, 4409, 4421, 4423, 4441, 4447, 4451, 4457, 4463, 4481, 4483, 4493,
                                                      4507, 4513, 4517, 4519, 4523, 4547, 4549, 4561, 4567, 4583, 4591, 4597,
                                                      4603, 4621, 4637, 4639, 4643, 4649, 4651, 4657, 4663, 4673, 4679, 4691,
                                                      4703, 4721, 4723, 4729, 4733, 4751, 4759, 4783, 4787, 4789, 4793, 4799,
                                                      4801, 4813, 4817, 4831, 4861, 4871, 4877, 4889, 4903, 4909, 4919, 4931,
                                                      4933, 4937, 4943, 4951, 4957, 4967, 4969, 4973, 4987, 4993, 4999, 5003,
                                                      5009, 5011, 5021, 5023, 5039, 5051, 5059, 5077, 5081, 5087, 5099, 5101,
                                                      5107, 5113, 5119, 5147, 5153, 5167, 5171, 5179, 5189, 5197, 5209, 5227,
                                                      5231, 5233, 5237, 5261, 5273, 5279, 5281, 5297, 5303, 5309, 5323, 5333,
                                                      5347, 5351, 5381, 5387, 5393, 5399, 5407, 5413, 5417, 5419, 5431, 5437,
                                                      5441, 5443, 5449, 5471, 5477, 5479, 5483, 5501, 5503, 5507, 5519, 5521,
                                                      5527, 5531, 5557, 5563, 5569, 5573, 5581, 5591, 5623, 5639, 5641, 5647,
                                                      5651, 5653, 5657, 5659, 5669, 5683, 5689, 5693, 5701, 5711, 5717, 5737,
                                                      5741, 5743, 5749, 5779, 5783, 5791, 5801, 5807, 5813, 5821, 5827, 5839,
                                                      5843, 5849, 5851, 5857, 5861, 5867, 5869, 5879, 5881, 5897, 5903, 5923,
                                                      5927, 5939, 5953, 5981, 5987, 6007, 6011, 6029, 6037, 6043, 6047, 6053,
                                                      6067, 6073, 6079, 6089, 6091, 6101, 6113, 6121, 6131, 6133, 6143, 6151,
                                                      6163, 6173, 6197, 6199, 6203, 6211, 6217, 6221, 6229, 6247, 6257, 6263,
                                                      6269, 6271, 6277, 6287, 6299, 6301, 6311, 6317, 6323, 6329, 6337, 6343,
                                                      6353, 6359, 6361, 6367, 6373, 6379, 6389, 6397, 6421, 6427, 6449, 6451,
                                                      6469, 6473, 6481, 6491, 6521, 6529, 6547, 6551, 6553, 6563, 6569, 6571,
                                                      6577, 6581, 6599, 6607, 6619, 6637, 6653, 6659, 6661, 6673, 6679, 6689,
                                                      6691, 6701, 6703, 6709, 6719, 6733, 6737, 6761, 6763, 6779, 6781, 6791,
                                                      6793, 6803, 6823, 6827, 6829, 6833, 6841, 6857, 6863, 6869, 6871, 6883,
                                                      6899, 6907, 6911, 6917, 6947, 6949, 6959, 6961, 6967, 6971, 6977, 6983,
                                                      6991, 6997, 7001, 7013, 7019, 7027, 7039, 7043, 7057, 7069, 7079, 7103,
                                                      7109, 7121, 7127, 7129, 7151, 7159, 7177, 7187, 7193, 7207, 7211, 7213,
                                                      7219, 7229, 7237, 7243, 7247, 7253, 7283, 7297, 7307, 7309, 7321, 7331,
                                                      7333, 7349, 7351, 7369, 7393, 7411, 7417, 7433, 7451, 7457, 7459, 7477,
                                                      7481, 7487, 7489, 7499, 7507, 7517, 7523, 7529, 7537, 7541, 7547, 7549,
                                                      7559, 7561, 7573, 7577, 7583, 7589, 7591, 7603, 7607, 7621, 7639, 7643,
                                                      7649, 7669, 7673, 7681, 7687, 7691, 7699, 7703, 7717, 7723, 7727, 7741,
                                                      7753, 7757, 7759, 7789, 7793, 7817, 7823, 7829, 7841, 7853, 7867, 7873,
                                                      7877, 7879, 7883, 7901, 7907, 7919
                                              };
        /// <summary>
        /// Basis
        /// </summary>
        private int basis;
        /// <summary>
        /// Current State
        /// </summary>
        private int numSequence;
        /// <summary>
        /// Seed
        /// </summary>
        private int seedRandom;
        #endregion

        #region Constructors
        /// <summary>
        /// Inicialize the generator
        /// </summary>
        /// <param name="seed">Generator seed</param>
        public QMCHaltonRandom(double seed)
        {
            try{
                if((seed < 0) | (seed >= 1)){
                    throw new Exception("seed out of range, it must be [0..1[");
                }
                this.seedRandom = (int)(seed * maxLong);
                this.Initialize();
            } catch(Exception e){
                throw new Exception("QMCHaltonRandom:" + e.Message);
            }
        }
        /// <summary>
        /// Inicialize the generator
        /// </summary>
        public QMCHaltonRandom()
        {
            try{
                int milliSecond = DateTime.Now.Millisecond;
                this.seedRandom = (int)(((double)milliSecond / (double)1000) * maxLong);
                this.Initialize();
            } catch(Exception e){
                throw new Exception("QMCHaltonRandom:" + e.Message);
            }
        }
        #endregion

        #region Auxiliar Methods
        /// <summary>
        /// Inicialize the values
        /// </summary>
        private void Initialize()
        {
            this.numSequence = 1;
            this.SetDimension(this.seedRandom);
        }
        /// <summary>
        /// Set the Dimension of the generator
        /// </summary>
        /// <param name="seedUsed">The seed used</param>
        private void SetDimension(int seedUsed)
        {
            this.basis = this.primeNumbers[seedUsed];
        }
        /// <summary>
        /// Gets a value from a line of the file
        /// </summary>
        /// <param name="line">The line from the file</param>
        private string getVal(string line)
        {
            if(line == ""){
                return "";
            }
            string t = line.Substring(0);
            return t;
        }
        #endregion

        #region IRandom Members
        /// <summary>
        /// Reinicialize the generator
        /// </summary>
        /// <param name="seed">Generator seed</param>
        public void ResetGenerator(int seed)
        {
            try{
                if((seed < 0) | (seed >= 1)){
                    throw new Exception("seed out of range, it must be [0..1[");
                }
                this.seedRandom = (int)(seed * maxLong);
                this.Initialize();
            } catch(Exception e){
                throw new Exception("QMCHaltonRandom:" + e.Message);
            }
        }
        /// <summary>
        /// Returns a random double
        /// </summary>
        /// <returns>value between 0 and 1</returns>
        public double NextDouble()
        {
            uint i;
            uint n1;
            int b = this.basis;
            uint n0 = (uint)this.numSequence;
            double h = 0.0;
            double ib = 1.0 / b;
            while(n0 > 0){
                n1 = n0 / (uint)b;
                i = n0 - n1 * (uint)b;
                h += ib * i;
                ib /= b;
                n0 = n1;
            }
            this.numSequence++;
            return (h);
        }
        #endregion
    }
}